Gaseous Fuel Spark-Ignited Internal Combustion Engine System

ABSTRACT

A system and method for reforming a portion of an exhaust gas stream in an internal combustion engine system. An exhaust gas recirculation assembly divides the exhaust gas stream into a recycle stream and a vent stream. A mixer in fluid receiving communication with the recycle stream forms a combination stream by mixing a gaseous fuel stream with the recycle stream. A thermochemical recuperator component fluidly connects to the mixer and includes a first flow path and a second flow path. The first flow path has a catalyst through which the combination stream flows to create a reformate stream, and the second flow path has a heat transfer area for transferring heat from the vent stream to the combination stream.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 61/784,726 entitled “GASEOUS FUEL SPARK-IGNITED INTERNALCOMBUSTION ENGINE SYSTEM” and filed on Mar. 14, 2013 the contents ofwhich incorporated herein by reference in their entirety.

FIELD

This disclosure relates to gaseous fuel engine systems, and moreparticularly relates to reforming a recycled portion of an exhaust gasstream.

BACKGROUND

Emissions regulations for internal combustion engines have become morestringent over recent years. Environmental concerns have motivated theimplementation of stricter emission requirements for internal combustionengines throughout much of the world. Governmental agencies, such as theEnvironmental Protection Agency (EPA) in the United States, carefullymonitor the emission quality of engines and set acceptable emissionstandards, to which all engines must comply. Generally, emissionrequirements vary according to engine type. Emission tests forspark-ignited gasoline (e.g., non-gaseous) engines typically monitor therelease of carbon monoxide, nitrogen oxides (NOx), and unburnedhydrocarbons (UHC). Catalytic converters (e.g., oxidation catalysts)implemented in an exhaust gas aftertreatment system have been used toeliminate many of the regulated pollutants present in exhaust gasgenerated from gasoline powered engines. For example, some knownthree-way catalysts include carefully selected catalytic materialformulations to specifically oxidize carbon monoxide and unburnedhydrocarbons, and reduce nitrogen oxides to less harmful components,present in the exhaust gas. Conventional three-way catalysts aredesigned to oxidize or reduce such pollutants more efficiently forengines running above the stoichiometric air-to-fuel ratio (i.e., richconditions).

Recently, due at least in part to high crude oil prices, environmentalconcerns, and future fuel availability, many internal combustion enginedesigners have looked to at least partially replace crude oil fossilfuels, e.g., gasoline and diesel, with so-called alternative fuels forpowering internal combustions engines. Desirably, by replacing orreducing the use of fossil fuels with alternative fuels, the cost offueling internal combustion engines is decreased, harmful environmentalpollutants are decreased, and/or the future availability of fuels isincreased. Known alternative fuels include gaseous fuels or fuels withgaseous hydrocarbons, such as, for example, natural gas, petroleum gas(propane), and hydrogen. The combustion byproducts present in exhaustgas generated by spark-ignited gaseous-powered engines are similar tothose present in exhaust gas generated by spark-ignitednon-gaseous-powered engines. Accordingly, conventional gaseous-poweredengine systems utilize the same oxidation catalysts found innon-gaseous-powered engine systems to oxidize the regulated pollutantsgenerated by gaseous-powered engines.

Traditionally, gaseous-powered engines are operated at rich air-to-fuelratios (e.g., richer than stoichiometric) in order to reduce oxygenconcentrations within the exhaust gas, and thus reduce the formation ofcarbon monoxide and nitrogen oxides. However, operating agaseous-powered engine under stoichiometric or richer air-to-fuel ratiosresults in a relatively low brake thermal efficiency of the engine.Moreover, operating at such air-to-fuel ratios causes high combustiontemperatures, which result in high component temperatures in the engine,and the necessity to reduce output power to avoid component failure.However, in view of the premium placed on satisfying exhaust emissionsregulations, conventional gaseous-powered engines are designed to meetexhaust emissions regulations at the expense of thermal efficiency andpower density.

SUMMARY

The subject matter of the present application has been developed inresponse to the present state of the art, and in particular, in responseto the problems and needs in the art of gaseous-fuel-powered internalcombustion engine systems that have not yet been fully solved bycurrently available systems. Accordingly, in certain embodiments, agaseous-fuel-powered internal combustion engine system is disclosedherein that improves the thermal efficiency and power density of theengine while meeting stringent exhaust emissions regulations. In otherwords, the control system and method described in the present disclosureovercomes many of the shortcomings of the prior art.

The present disclosure relates to an engine system that includes anexhaust gas aftertreatment sub-system that is fluidly connected to anexhaust manifold of an internal combustion engine for receiving anexhaust gas stream. The system further includes an exhaust gasrecirculation assembly fluidly connected to the exhaust gasaftertreatment sub-system. The exhaust gas recirculation assemblydivides the exhaust gas stream into a recycle stream and a vent stream.The system also includes a mixer in fluid receiving communication withthe recycle stream that forms a combination stream by mixing a gaseousfuel stream with the recycle stream. The system further includes athermochemical recuperator component fluidly connected to the mixer. Thethermochemical recuperator component includes a first flow path that hasa catalyst through which the combination stream flows to create areformate stream. The thermochemical recuperator component furtherincludes a second flow path comprising a heat transfer area fortransferring heat from the vent stream to the combination stream.

In one embodiment, the reformate stream may be a hydrogen enrichedgaseous stream. The exhaust gas aftertreatment sub-system may be athree-way catalyst. Also, in one embodiment, the exhaust gas stream mayhave, at most, trace amounts of oxygen. The gaseous fuel stream may benatural gas and the system may further include a sulfur scrubberupstream of the thermochemical recuperator component. The system mayfurther include a fuel pre-heater that transfers heat from the ventstream to the gaseous fuel stream. The system may also include areformate stream cooler and a second mixer to form an intake stream bycombining the reformate stream with an air stream. In oneimplementation, the system may include a filter disposed in thereformate stream and may also include a turbocharger with a turbineupstream of the exhaust gas recirculation assembly.

In one specific example of an implementation of the system of thepresent disclosure, the engine system includes a natural gas enginecomprising an intake manifold and an exhaust manifold. The specificsystem includes an exhaust gas aftertreatment sub-system that is fluidlyconnected to the exhaust manifold for receiving an exhaust gas stream.This exhaust gas aftertreatment sub-system includes a three-waycatalyst. The specific system further includes an exhaust gasrecirculation assembly fluidly connected to the exhaust gasaftertreatment sub-system for dividing the exhaust gas stream into arecycle stream and a vent stream. Also included is a fuel pre-heater influid receiving communication with the vent stream so that heat from thevent stream is transferred to a gaseous fuel stream. Also, a mixer isincluded in the specific implementation of the system for forming acombination stream by mixing the gaseous fuel stream with the recyclestream. The specific system also includes a thermochemical recuperatorcomponent fluidly connected to the mixer, wherein the thermochemicalrecuperator has a first flow path that has a catalyst through which thecombination stream flows to create a hydrogen-enriched reformate stream.The thermochemical recuperator component further has a second flow pathwith a heat transfer area for transferring heat from the vent stream tothe combination stream. Finally, the specific system includes a secondmixer in fluid receiving communication with the reformate stream thatforms an intake stream by combining the reformate stream with an airstream.

Also disclosed in the present disclosure is a method for reforming aportion of an exhaust gas stream. The method includes dividing anexhaust gas stream from an engine into a recycle stream and a ventstream. The method further includes mixing the recycle stream with agaseous fuel stream to form a combination stream. Finally, the methodincludes catalytically converting the combination stream into ahydrogen-enriched reformate stream. In one implementation, catalyticallyconverting the combination stream into a hydrogen-enriched reformatestream involves flowing the combination stream through a first flow pathof a thermochemical recuperator component and flowing the vent streamthrough a second flow path of the thermochemical recuperator component.The first flow path has a catalyst for reacting the combination streamand the second flow path has a heat transfer area for transferring heatfrom the vent stream to the combination stream. In one implementation,the method may further include removing oxygen from the exhaust gasstream before catalytically converting the combination stream into ahydrogen-enriched reformate stream. For example, oxygen may be removedby operating the engine at an air/fuel ratio that is stoichiometric orfuel rich or by implementing a three-way catalyst in an exhaust gasaftertreatment sub-system to remove the oxygen.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present disclosure should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the subject matter disclosedherein. Thus, discussion of the features and advantages, and similarlanguage, throughout this specification may, but do not necessarily,refer to the same embodiment.

Furthermore, the described features, advantages, and characteristics ofthe disclosure may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize that thesubject matter of the present application may be practiced without oneor more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments of the disclosure. Further, in some instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the subject matter of the presentdisclosure. These features and advantages of the present disclosure willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the disclosure as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the disclosure will be readilyunderstood, a more particular description of the disclosure brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the subjectmatter of the present application will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings, in which:

FIG. 1 is a schematic block diagram of a system for reforming a recycledportion of an exhaust gas stream to improve engine efficiency, accordingto one embodiment;

FIG. 2 is a schematic block diagram of a system for reforming a recycledportion of an exhaust gas stream to improve engine efficiency, accordingto another embodiment;

FIG. 3 is a schematic block diagram of a system for reforming a recycledportion of an exhaust gas stream to improve engine efficiency, accordingto yet another embodiment; and

FIG. 4 is a schematic flow chart diagram of a method for reforming arecycled portion of an exhaust gas stream to improve engine efficiency,according to one embodiment.

DETAILED DESCRIPTION

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment. Similarly, the use of theterm “implementation” means an implementation having a particularfeature, structure, or characteristic described in connection with oneor more embodiments of the present disclosure, however, absent anexpress correlation to indicate otherwise, an implementation may beassociated with one or more embodiments.

FIG. 1 is a schematic block diagram of a system 100 for reforming arecycled portion of an exhaust gas stream to improve engine efficiency,according to one embodiment. The system 100 includes an internalcombustion engine 110, an exhaust gas aftertreatment sub-system 120, anexhaust gas recirculation assembly 130, a mixer 140, a thermochemicalrecuperator component 150, and a second mixer 160. Generally, the system100 is configured so that an exhaust gas stream 12 exiting the exhaustmanifold 112 of an internal combustion engine 110 flows into an exhaustgas aftertreatment sub-system 120. As described below in greater detail,the exhaust gas aftertreatment sub-system 120 may include variouscomponents, such as a hydrocarbon oxidation catalyst, a particulatefilter, and/or a nitrogen oxide reduction catalyst, among others. Theexhaust gas stream 12 is then divided into two separate streams 32, 34by an exhaust gas recirculation assembly 130. The two streams 32, 34 area recycle stream 32 and a vent stream 34. The exhaust gas recirculationassembly 130 may include a piping manifold and/or various valves todivide the exhaust gas stream 12 into a recirculating portion (recyclestream 32) and a portion that vents to the atmosphere (vent stream 34).

In the depicted embodiment of the system 100, the recycle stream 32flows into a mixer 140 where it is combined and mixed with a gaseousfuel stream 5. In one embodiment, the mixer 140 may be a portion oftubing/piping. In another embodiment, the mixer 140 may include achamber where the gaseous fuel stream 5 and the recycle stream 32 arecombined. In yet another embodiment, the mixer 140 may include mixingelements, such as baffles or actuators, which promote the mixing of thetwo gaseous streams into a combination stream 42. The combination stream42 then flows into a thermochemical recuperator component 150. Thethermochemical recuperator component 150 has two separate flow paths, afirst flow path with a catalyst and a second flow path with a heattransfer area. The combination stream 42 flows through the first flowpath and a portion of the molecules adsorb onto the surface of thecatalyst and react to convert the combination stream into ahydrogen-enriched reformate stream 52 (further details are includedbelow regarding the catalyst). The vent stream 34 from the exhaust gasrecirculation assembly 130 flows through the second flow path andtransfers heat across the heat transfer area to the combination stream42. In one embodiment, the combination stream 42 and/or the catalyst inthe first flow path of the thermochemical recuperator component 150 mustbe at a certain temperature in order to effectively and efficientlyreact.

The reformate stream 52 then flows to a second mixer 160 to be combinedwith an air stream 6 in order to form an intake stream 62. In oneembodiment, the second mixer 160 may be a portion of tubing/piping. Inanother embodiment, the second mixer 160 may include a chamber where thereformate stream 52 and the air stream 6 are combined. In yet anotherembodiment, the second mixer 160 may include mixing elements, such asbaffles or actuators, which promote the mixing of the two gaseousstreams in order to form the intake stream 62.

FIG. 2 is a schematic block diagram of a system 200 for reforming arecycled portion of an exhaust gas stream to improve engine efficiency,according to another embodiment. According to one specific embodiment ofthe internal combustion engine system 200 shown schematically in FIG. 2,the system 200 includes an internal combustion engine 110 that has anintake manifold 111 and an exhaust manifold 112. The engine 110 may be aspark-ignited engine fueled by gaseous hydrocarbons, such as naturalgas, petroleum gas (propane), and hydrogen, and operated understoichiometric conditions. As defined herein, gaseous fuels, as opposedto non-gaseous fuels (e.g., gasoline and diesel), are those that areintroduced and managed within the engine in a gaseous state, as opposedto, a liquid or solid state. In FIG. 2, the depicted engine 110 is aspark-ignited engine fueled by natural gas. Spark-ignited gaseous fuelengines are configured and calibrated differently than spark-ignitednon-gaseous fuel engines. Gaseous fuel engines introduce considerationsnot present with non-gaseous engines. For example, non-gaseous enginesdo not produce significant amounts of certain combustion byproductsproduced by gaseous engines. Gaseous fuel engines typically producelarge amounts of methane when the gaseous fuel itself contains a largeamount of methane, which is normal with natural gas and a wide varietyof other gaseous fuels.

The system 200 depicted in FIG. 2 includes various additional componentsthat may be implemented with the present disclosure. For example, aturbocharger 115, a fuel pre-heater 145, and an auxiliary air/fuelinjector 165, among others, may also be included in the system 200. Theair stream 6 includes an air inlet that is at essentially atmosphericpressure, thus enabling fresh air to enter the system 200. The fresh airis mixed with the reformate stream 52 in the second mixer 160.Additional gaseous fuel can be added to the air/fuel mixture downstreamof the second mixer 160 and compressor 116 in the form of an auxiliaryfuel injector 165 for more precisely dithering the air-to-fuel ratio ofthe mixture prior to entering the engine 110. Although the auxiliaryinjector 165 is depicted as directly injecting air/fuel into the intakemanifold 111, it is contemplated that the auxiliary injector 165 mayinjected at other locations upstream of the combustion chambers of theengine 110.

In operation, the air/fuel mixture from the second mixer 160 iscompressed by the compressor 116 to increase the pressure and density ofthe mixture. The compressor 116 is co-rotatably driven by a turbine 117of the turbocharger 115, which is driven by the exhaust gas stream 12from the engine 110, as is known in the art. Although not depicted, thecompressed air/fuel mixture may then flow into a charge air cooler,which decreases the temperature of the intake air charge for sustainingthe use of a denser intake charge into the engine 110. Followingcooling, the air/fuel mixture is directed into the combustion chambersof the engine 110. The air/fuel mixture may be ignited via aspark-ignition system, and the fuel is combusted to generate thepressure differential within the chambers for powering the engine 110and various auxiliary devices, such as an alternator.

Combustion of the fuel produces exhaust gas that is operatively ventedinto the exhaust gas manifold 112. After exiting the engine 110, theexhaust gas drives the turbine 117 of the turbocharger 115. The exhaustgas aftertreatment sub-system 120 can include one or more exhausttreatment components, such as, for example, three-way catalysts,oxidation catalysts, filters, adsorbers, and the like, for treating(i.e., removing pollutants from) the exhaust gas stream 12. Inparticular embodiments, the exhaust gas aftertreatment sub-system 120includes an advanced three-way catalyst. In certain implementations, thethree-way catalyst is a flow-through type catalyst having a catalyst bedexposed to the exhaust gas flowing through the main exhaust line andpast the bed. The catalyst bed includes a catalytic layer disposed on awashcoat or carrier layer. The carrier layer can include any of variousmaterials (e.g., oxides) capable of suspending the catalytic layertherein. The catalyst layer is made from one or more catalytic materialsselected to react with (e.g., oxidize) one or more pollutants in theexhaust gas. The catalytic materials of the three-way catalyst caninclude any of various materials, such as precious metals platinum,palladium, and rhodium, as well as other materials, such as transitionmetals cerium, iron, manganese, and nickel. Further, the catalystmaterials can have any of various ratios relative to each other foroxidizing and reducing relative amounts and types of pollutants asdesired. Generally, the three-way catalyst contains catalytic materialsspecifically selected to react with and oxidize or reduce three specificpollutants. The three specific pollutants include carbon monoxide (CO),unburned hydrocarbons (UHC), and nitrogen oxides (NOx). In oneembodiment the three-way catalyst is a single integrated element and inanother embodiment the three-way catalyst may include multiple catalystselements at various locations in the aftertreatment sub-system 120.

The exhaust gas recirculation assembly 130 includes actuators and valvesto direct exhaust gas 12 to one or more destinations. For example, theexhaust gas recirculation assembly 130 can include an EGR valve that isactuatable to direct (e.g., vent) a portion of the received exhaust gasinto the atmosphere as expelled exhaust (vent stream 34) and direct aportion of the received exhaust gas into an exhaust gas recirculation(EGR) line (recycle stream 32) for recirculation back into thecombustion chambers of the engine 110.

The system 200 may also include a fuel pre-heater 145, thermochemicalrecuperator 150, a mixer 140, and a reformate cooler (not depicted). Agaseous fuel, which in the illustrated embodiment is natural gas, issupplied from a fuel source, such as a gaseous fuel compression tank, tothe pre-heater 145. The pre-heater 145 can be a flow-through heatexchanger with coils in exhaust receiving communication with the ventstream 34 of the exhaust gas stream 12. The gaseous fuel stream 5, e.g.,natural gas, is passed over the coils, and heat from the coils istransferred into the gaseous fuel stream 5, which increases thetemperature of the fuel. From the pre-heater 145, the vent stream 34 maybe expelled from the system 200 and the heated gaseous fuel stream 5 isdirected into a mixer 140. The mixer 140 also receives a recycle stream32 through an EGR line of the recirculation assembly 130. The mixer 140combines and mixes the heated gaseous fuel stream 5 with the recyclestream 32 to form a combination stream 42.

From the mixer 145, the combination stream 42 flows into thethermochemical recuperator component 150, which also receives heat fromthe vent stream 34. Similar to the pre-heater 145, the thermochemicalrecuperator component 150 can include flow-through heat exchangercomponents, such as coils in exhaust receiving communication with thevent stream 34 from the recirculation assembly 130. The combinationstream 42 is passed over the coils, and heat from the coils istransferred into the combination stream 42, which increases thetemperature of the mixture. Unlike the pre-heater 145, thethermochemical recuperator component 150 also includes a catalyst bedcoated with catalytic materials. As the combination stream 42 passesthrough the thermochemical recuperator component 150 and is heated, theheated mixture also passes over the catalytic materials, whicheffectuate chemical reactions within the combination stream 42 to formnew chemical compositions.

When the temperature within the recuperator component 150 reachespredetermined temperature thresholds (e.g., between about 600° C. andabout 1,100° C. in some implementations), the catalytic materials of thethermochemical recuperator component 150 effectively increase the energyratio/density of the combination stream 42 by promoting desirablechemical reactions. For example, the catalytic materials may include ahigh nickel concentration, which promotes the combination ofhydrocarbons (from the gaseous fuel stream 5) with water vapor (from therecycle stream 32) to generate a reformate stream 52 enriched withhydrogen and carbon monoxide. The combustion of gaseous fuels, such asnatural gas, generates sufficient water vapor to sustain the reformingreactions. Moreover, the components in the exhaust gas aftertreatmentsub-system 120 result in a processed exhaust gas stream 12 that isessentially void of oxygen and consisting mainly of water vapor, carbondioxide, and nitrogen, according to one embodiment. In one embodiment,the presence of oxygen in the exhaust gas reduces the efficacy of thereforming reactions taking place in the thermochemical recuperatorcomponent 150. For this reason, the recirculation assembly 130 ispositioned downstream of the aftertreatment sub-system 120, where theoxygen content of the exhaust gas stream has been reduced by thethree-way catalyst. Further, certain exothermic processes performed bythe three-way catalyst (e.g., the oxidation of carbon monoxide andunburned hydrocarbons) increases the temperature of the exhaust gasstream 12. Accordingly, positioning the thermochemical recuperatorcomponent 150 downstream of the exhaust gas aftertreatment sub-system120 utilizes the hotter exhaust gas exiting to promote the reformingreactions within the recuperator.

This chemically-altered fuel/EGR mixture is defined as the reformatestream 52, which exits the recuperator component 150 and may flow into avariety of other processing components, such as a reformate cooler. Thereformate cooler may also include coils over which the reformate stream52 passes. Coolant may flow through the coils in order to lower thetemperature of the reformate stream 52. The cooled reformate stream 52is then combined with air in the second mixer 160 to form an intakestream 62. The intake stream 62 flows through the compressor 116 of theturbocharger 115 and then to the intake manifold 11 of the engine 110,as discussed above. Cooling the reformate stream 52 increases thedensity of the stream and improves the engine efficiency and power.

FIG. 3 is a schematic block diagram of a system 300 for reforming arecycled portion of an exhaust gas stream to improve engine efficiency,according to yet another embodiment. The depicted system 300 includesadditional features that may be included in an engine system of thepresent disclosure. For example, the engine system 300 includes anengine, an advanced three-way catalyst, a thermochemical recuperator 150downstream of the catalyst, a fuel pre-heater 145, a mixer 140, and asecond mixer 160, among other components. The depicted system 300 mayfurther include a reformate cooler 238, various temperature sensors,control valves, and pressure regulators as indicated, which can becontrolled by various modules of an electronic control module orcontroller. Additionally, the engine system 300 includes a reformatefilter 250 downstream of the reformate cooler 238 to filter outparticulate matter and other constituents that are potentially harmfulto the engine 110. The filter 250 may include a heater to increase thetemperature of the reformate above a condensation level of thereformate. The engine system 300 also includes a sulfur scrubber 254upstream of the pre-heater 145 and upstream of a dithering fuel injector214. Sulfur degrades the components of the recuperator 150 and theengine 110. Accordingly, the sulfur scrubber 254 reduces the sulfurcontent in the gaseous fuel prior to the fuel entering the recuperator150 and engine 110.

The internal combustion engine system 300 also includes an insulationsystem that insulates the exhaust aftertreatment sub-system 120 and thefuel delivery system. Because the efficiency of the reforming reactionswithin the thermochemical recuperator 150 is sensitive to thetemperature of the gaseous fuel stream 5 and the recycle stream 32, theinsulation system is configured to reduce heat losses from the exhaustand fuel delivery systems. The insulation system includes exhaustinsulation that insulates (e.g., is wrapped around) the variouscomponents and plumping of the exhaust system, and fuel deliveryinsulation that insulates the various components and plumping of thefuel delivery system.

The system 300 may also include various valves, gauges, controllers, andactuators and how each of these elements may be configured in order tocontrollably operate the system 300. In addition, various additionalcomponents, such as air filters, sensors, pumps, throttles, etc, mayalso be implemented in certain embodiments of the system. It iscontemplated that these additional components and elements (notdepicted) fall within the scope of the present disclosure.

FIG. 4 is a schematic flow chart diagram of a method 400 for reforming arecycled portion of an exhaust gas stream to improve engine efficiency,according to one embodiment. The method 400 first includes dividing anexhaust gas stream 12 from an engine 110 into a recycle stream 32 and avent stream 34 at 402. The method 400 then includes mixing the recyclestream 32 with a gaseous fuel stream 5 to form a combination stream 42at 404. Further, the method 400 includes catalytically converting thecombination stream 42 into a hydrogen-enriched reformate 52 stream at406. As described above, various additional steps may be implementedwith this method 400, such as removing oxygen from the exhaust gasstream 12 before catalytically converting the combination stream 42 intoa hydrogen-enriched reformate stream 52. For example, the engine 110 maybe operated at an air/fuel ratio that is stoichiometric or fuel rich inorder to prevent excess oxygen in the exhaust gas stream 12. In otherembodiments, various other processing components, such as those found inthe aftertreatment sub-system 120, may actively remove/reduce oxygen.

The described features, structures, advantages, and/or characteristicsof the subject matter of the present disclosure may be combined in anysuitable manner in one or more embodiments and/or implementations. Inthe above description, numerous specific details are provided to imparta thorough understanding of embodiments of the subject matter of thepresent disclosure. One skilled in the relevant art will recognize thatthe subject matter of the present disclosure may be practiced withoutone or more of the specific features, details, components, materials,and/or methods of a particular embodiment or implementation. In otherinstances, additional features and advantages may be recognized incertain embodiments and/or implementations that may not be present inall embodiments or implementations. Further, in some instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the subject matter ofthe present disclosure. The features and advantages of the subjectmatter of the present disclosure will become more fully apparent fromthe above description and appended claims, or may be learned by thepractice of the subject matter as set forth above.

In the above description, certain terms may be used such as “up,”“down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” andthe like. These terms are used, where applicable, to provide someclarity of description when dealing with relative relationships. But,these terms are not intended to imply absolute relationships, positions,and/or orientations. For example, with respect to an object, an “upper”surface can become a “lower” surface simply by turning the object over.Nevertheless, it is still the same object. Further, the terms“including,” “comprising,” “having,” and variations thereof mean“including but not limited to” unless expressly specified otherwise. Anenumerated listing of items does not imply that any or all of the itemsare mutually exclusive and/or mutually inclusive, unless expresslyspecified otherwise. The terms “a,” “an,” and “the” also refer to “oneor more” unless expressly specified otherwise.

Additionally, instances in this specification where one element is“coupled” to another element can include direct and indirect coupling.Direct coupling can be defined as one element coupled to and in somecontact with another element. Indirect coupling can be defined ascoupling between two elements not in direct contact with each other, buthaving one or more additional elements between the coupled elements.Further, as used herein, securing one element to another element caninclude direct securing and indirect securing. Additionally, as usedherein, “adjacent” does not necessarily denote contact. For example, oneelement can be adjacent another element without being in contact withthat element.

The schematic flow chart diagrams and method schematic diagramsdescribed above are generally set forth as logical flow chart diagrams.As such, the depicted order and labeled steps are indicative ofrepresentative embodiments. Other steps, orderings and methods may beconceived that are equivalent in function, logic, or effect to one ormore steps, or portions thereof, of the methods illustrated in theschematic diagrams.

Additionally, the format and symbols employed are provided to explainthe logical steps of the schematic diagrams and are understood not tolimit the scope of the methods illustrated by the diagrams. Althoughvarious arrow types and line types may be employed in the schematicdiagrams, they are understood not to limit the scope of thecorresponding methods. Indeed, some arrows or other connectors may beused to indicate only the logical flow of a method. For instance, anarrow may indicate a waiting or monitoring period of unspecifiedduration between enumerated steps of a depicted method. Additionally,the order in which a particular method occurs may or may not strictlyadhere to the order of the corresponding steps shown.

As used herein, the phrase “at least one of”, when used with a list ofitems, means different combinations of one or more of the listed itemsmay be used and only one of the items in the list may be needed. Theitem may be a particular object, thing, or category. In other words, “atleast one of” means any combination of items or number of items may beused from the list, but not all of the items in the list may berequired. For example, “at least one of item A, item B, and item C” maymean item A; item A and item B; item B; item A, item B, and item C; oritem B and item C. In some cases, “at least one of item A, item B, anditem C” may mean, for example, without limitation, two of item A, one ofitem B, and ten of item C; four of item B and seven of item C; or someother suitable combination.

The present subject matter may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

1. An engine system, comprising: an exhaust gas recirculation assemblyfluidly connected to an exhaust manifold of an internal combustionengine, the exhaust gas recirculation assembly configured to divide anexhaust gas stream into a recycle stream and a vent stream; a mixer influid receiving communication with the recycle stream, the mixerconfigured to form a combination stream by mixing a gaseous fuel streamwith the recycle stream; and a thermochemical recuperator componentfluidly connected to the mixer, wherein the thermochemical recuperatorincluding: a first flow path comprising a catalyst through which thecombination stream flows to create a reformate stream, and a second flowpath comprising a heat transfer area for transferring heat from the ventstream to the combination stream.
 2. The engine system of claim 1,wherein the reformate stream comprises a hydrogen enriched gaseousstream.
 3. The engine system of claim 1, further comprising an exhaustgas aftertreatment sub-system fluidly connected between the exhaustmanifold of an internal combustion engine and the exhaust gasrecirculation assembly.
 4. The engine system of claim 3, wherein theexhaust gas aftertreatment sub-system includes a three-way catalyst. 5.The engine system of claim 1, wherein the gaseous fuel stream comprisesnatural gas.
 6. The engine system of claim 1, further comprising asulfur scrubber positioned upstream of the thermochemical recuperatorcomponent.
 7. The engine system of claim 1, further comprising a fuelpre-heater, the pre-heater configured to transfer heat from the ventstream to the gaseous fuel stream.
 8. The engine system of claim 1,further comprising a reformate stream cooler, the reformate streamcooler configured to lower the temperature of the reformate stream. 9.The engine system of claim 1, further comprising a second mixer, thesecond mixer configured to combine the reformate stream with an airstream so as to form an intake stream for routing to the internalcombustion engine.
 10. The engine system of claim 1, further comprisinga filter disposed in the reformate stream, the filter configured toremove selected particulate matter from the reformate stream.
 11. Theengine system of claim 1, further comprising a turbocharger with aturbine upstream of the exhaust gas recirculation assembly.
 12. Anengine system, comprising a natural gas engine including an intakemanifold and an exhaust manifold; an exhaust gas recirculation assemblyfluidly connected to the exhaust manifold, the exhaust gas recirculationassembly configured to divide an exhaust gas stream into a recyclestream and a vent stream; a mixer in fluid receiving communication withthe recycle stream, the mixer configured to form a combination stream bymixing the gaseous fuel stream with the recycle stream; and athermochemical recuperator component fluidly connected to the mixer,wherein the thermochemical recuperator comprises: a first flow pathcomprising a catalyst through which the combination stream flows tocreate a hydrogen-enriched reformate stream, and a second flow pathcomprising a heat transfer area for transferring heat from the ventstream to the combination stream.
 13. The engine system of claim 12,further comprising a second mixer in fluid receiving communication withthe reformate stream, the second mixer configured to form an intakestream by combining the reformate stream with an air stream.
 14. Theengine system of claim 12, further comprising an exhaust gasaftertreatment sub-system fluidly connected between the exhaust manifoldand the exhaust gas recirculation assembly.
 15. The engine system ofclaim 14, wherein the exhaust gas aftertreatment sub-system includes athree-way catalyst.
 16. The engine system of claim 12, furthercomprising a fuel pre-heater in fluid receiving communication with thevent stream and configured to transfer heat from the vent stream to agaseous fuel stream;
 17. A method for reforming a portion of an exhaustgas stream, the method comprising: dividing the exhaust gas stream froman engine into a recycle stream and a vent stream; mixing the recyclestream with a gaseous fuel stream to form a combination stream; andcatalytically converting the combination stream into a hydrogen-enrichedreformate stream.
 18. The method of claim 17, wherein catalyticallyconverting the combination stream into a hydrogen-enriched reformatestream includes flowing the combination stream through a first flow pathof a thermochemical recuperator component and flowing the vent streamthrough a second flow path of the thermochemical recuperator component,wherein the first flow path comprises a catalyst for reacting thecombination stream and the second flow path comprises a heat transferarea for transferring heat from the vent stream to the combinationstream.
 19. The method of claim 17, further comprising pre-heating thegaseous fuel stream by transferring heat from the vent stream to thegaseous fuel stream.
 20. The method of claim 17, further comprisingcooling the hydrogen-enriched reformate stream.
 21. The method of claim17, further comprising removing oxygen from the exhaust gas streambefore catalytically converting the combination stream into ahydrogen-enriched reformate stream.
 22. The method of claim 21, whereinremoving oxygen from the exhaust gas stream comprises operating theengine at an air/fuel ratio that is one of stoichiometric and fuel rich.23. The method of claim 21, wherein a three-way catalyst is used in theremoving of oxygen from the exhaust gas stream